Mechanism for firing explosives



Nov. 14, 1961 M. B. CONRAD 3,008,411

MECHANISM FOR FIRING EXPLOSIVES Original Filed Feb. 6, 1959 JNVEN TOR.

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United State M 1959. This application Sept. 13, 1960, Ser. No. 56,631 1 Claim. (Cl. 10221.8)

This invention relates to the firing of explosives at desired levels of a well, such as an oil well. For example, the well casing is often perforated to permit oil to enter the well from an oil bearing stratum. Explosives are commonly employed for driving projectiles through the wall of the casing at the appropriate level. Also, at times, it is desirable to create an explosive pressure in the well, below the casing, for increasing the flow of oil. Explosives for this purpose are lowered into the well bottom, and are fired in various ways.

It is one of the objects of this invention to improve and simplify, in general, firing devices capable of causing explosions in the well or below the well casing.

This application is a continuation of my application Serial No. 791,557, filed February 6, 1959, now abandoned, and entitled Mechanism for Firing Explosives.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of one embodiment of the invention. For this purpose, there is shown a form in the drawings accompanying and forming part of the present specification. This form will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best defined by the appended claim.

Referring to the drawings:

FIGURE 1 is a longitudinal sectional view of an apparatus incorporating the invention, shown as in inactive position in a tube guide;

FIG. 2 is a view similar to FIG. 1, but showing the operating position, the firing pin being released;

FIG. 3 is a sectional view, taken along a plane corresponding to line 3-3 of FIG. 1; and

FIG. 4 is a general view on a reduced scale, mainly in elevation, of an apparatus incorporating the invention, shown as lowered into well casing.

In the present instance, the firing device is adapted to be guided by a hollow tube 2 which terminates at a predetermined distance within the well casing 1. As the firing device emerges from the tube 2, it causes explosives to be fired, contained in the conical devices 3, serially connected by a primer or fuse cord 4 having a thin metal cover. Such an arrangement is disclosed in a prior application filed in the name of John B. McElheny on April 7, 1958, under Serial No. 726,709, and entitled Oil Well Casing Perforator. These conical shells also contain projectiles or bullets fired through the thin walls of the shells, and adapted to penetrate the well casing 1. The firing device may be urged downwardly through the guide tube 2 either by gravity or by fluid pressure, as by 3,008,411 Patented Nov. 14, 1961 2 an aperture into which is pinnedthe lower cylindrical extension 8 of the post 6. I

Thebody 7 carries a fiat hook-like member 10 integrally.formedtherewith. This body 7 and member 10 have spaced-apart pads or projections 9 and 13 on opposite sides of the body so as to maintain the body 7 in true perpendicular position while the firing device is within the tubular guide 2 (see FIG. 3). A pivot pin 11 extends through the member 10. This member 10 is accommodated in a slot 10a formed at the upper cylindrical end 17 of support member 18. The hook end 12 of member 10 restrains a firing pin 14 against firing movement. This position is shown in FIG. 1. For this purpose, an enlarged head 15 of the pin 44 is provided with an appropriate recess '16 for the accommodation of the hook 12. Furthermore, the upper surface of the hook 12 and the lower engaging surface of the recess 16 are sloping, as indicated, so as to assure completely disengagement of the head 15 when the hook 12is moved angularly about the pivot pin 11, as shown in FIG. 2. In this releasing position, the firing pin 14 has been released to perform the firing operation. The pin 14 is urged downwardly by the hydraulic pressure existing in the well operating on the upper exposed surface of the head 15.

The head 1'5 is guided in an upper arcuate guiding portion 19 of the support member 18. Attached, as by screws 20 to the outer surface of this arcuate guide, is a pad or projection 21 serving to maintain the support member 18 in proper vertical position when it is within the tube 2.

The lower end 22 of the pin 14 is enlarged and carries a firing pin proper 23. It passes through an opening 25 in the upper end of a plug 24. This opening 25 may be provided with one or more O-rings 26 for sealing the space 27 within the plug 24, and so as to maintain a booster charge dry.

Threaded into the lower end of the support 18 is a threaded end 28 of a booster carrying body 29. This body 29 has a recess 30 opening upwardly in which a cartridge 31 may be accommodated. This cartridge is appropriately held in place by a collar 32 seating within a counterbore in recess 30. An O-ring 33, disposed around the reduced lower end of the plug 24, serves to provide a seal for the interior of the plug 24.

The body 29 has a downwardly directed recess 34 separated from the recess 30 by the thin wall 35. The upper recess 30 is filled with a primer 36 which may be designated as a dry booster. The lower recess 34 may be filled with a booster 37 which may be moistened by virtue of its position in the well. However, this booster is isolated from the dry booster 36 by virtue of the wall 35. When the firing pin 14 is in the firing position of FIG. 2, the igniting of the dry charge 36 serves to disrupt the wall 35; and there is sufiicient generation of heat to fire the wet booster charge 37. This booster 37 is directly connected to the primer cord 4. This primer cord -4 is supported by a nipple 38 threaded into a lower end of the body 29. The gland structure 39, disposed at the lower end of the nipple 38, serves to maintain the primer cord 4 in proper position, and also to seal the nipple 38 against the cord 4. A protecting shell 40 may be suspended from the body 29, as by the aid of the headless screws 41, engaging the bottom of a groove formed in the lower end of the body 29.

In operation, the guide tubing 2 is lowered to the dethe place where the firing is to ,take place. When the pad 13 moves downwardly out of the tubing 2, the book 12 is disengaged from the firing pin head 15. The fluid pressure is such'as to provide relative misalignment of the axes of members '7 and 18. The pin 14, being released, is urged by hydraulic pressure downwardly to the firing position of FIG. 2. Due to the provision of the O-rings 26 and 33, the dry booster charge 36 is prevented from being moistened arid the wall 35 is disrupted to ignite and fire the charge" 37 in recess 34.

The inventor claims: r

In a mechanism for usein a wellwa hollow guide adapted to extend intothe well; a single restraining hook member having means for guiding its descent'into the well iii said guide; a" yielding head carried by the hook members and urged into sealingcontact with the guide;

said guiding means being effectiveonly until the hook member extends out of the hollow guide; a body carried by the hook member and also guided ,by the hollow guide; a pivotal connection between the body and the hookmember; a firing mechanism including a firing pin restrained'by the hook against firing, said firingjmechanism being carried within the body;gsaid hook member being free to pivot about the 'pivotal connection for freeing said pin upon exit of the hook member from the hol-' low'guide, said yielding head accommodating itself in pivotal connection. 3 V V V lNo references cited. 

